Implementing integrated circuit chip attach in three dimensional stack using vapor deposited solder Cu pillars

1. A structure for implementing an interconnect individual integrated circuit (IC) chip attach in a three dimensional (3D) stack comprising:

an interconnect for joining IC chips;

said interconnect including a plurality of hollow copper pillars, and

said hollow copper pillars being coated with lead free solder using vapor deposition, said lead free solder coated hollow copper pillars being coated with an aluminum copper alloy Al(Cu) alloy for electromigration mitigation.